The present invention relates to a switch arranged on a portable electric device such as an electric shaver or a hair dryer.
Japanese Laid-Open Patent Publication No. 2010-104792 describes a prior art example of a switch for an electric shaver. The switch includes a push button and a lock assembly, which is shifted between an unlock state for permitting actuation of the button and a lock state for prohibiting actuation of the button. The lock assembly includes an operation ring and a lock ring. The operation ring is rotated about the button and moved between an unlock position, which corresponds to the unlock state, and a lock position, which corresponds to the lock state. The lock ring rotates integrally with the operation ring. The lock ring includes a rotational positioning portion. When the operation ring is located between the unlock position and lock position, the positioning portion is resiliently deformed by a fixed positioning portion, which is fixed to a case of an electric shaver. The resilient force produced when the rotational positioning portion is resiliently deformed guides the operation ring to the unlock position or lock position. The lock ring includes a hook. When the lock ring is located at the lock position, the hook comes into contact with the button and prohibits actuation of the button.
The rotational positioning portion and hook are formed integrally with the lock ring. This reduces the freedom for selection of the material of the lock ring. For example, there is a need to select a material that has resiliency suitable for the rotational positioning portion and rigidity suitable for the hook. When the freedom for material selection is small, it is difficult to form a lock assembly that provides satisfactory tactility and rigid lock strength.
The switch of the above '792 publication is assembled by holding the button between the lock ring and the operation ring. Thus, before the switch is coupled to a completed product such as an electric shaver, a test cannot be performed to determine whether the button can be pushed. For example, a test cannot be performed to determine whether the electric shaver functions normally when the button is pushed. The same applies when testing whether rotational force of the operation ring and lock ring can be transmitted when the button is held between the operation ring and lock ring. For example, a test cannot be performed to determine whether these components are properly coupled to each other and rotate integrally with each other. This may increase the operational defect rate of the switch in a completed product and lower the assembly efficiency.